[25/30] mds: bring back old style backtrace handling

From: "Yan, Zheng" <zheng.z.yan@intel.com>

On 05/28/2013 04:08 AM, Sage Weil wrote:
> On Mon, 27 May 2013, Yan, Zheng wrote:
> 
[ snip ]
>> @@ -1028,6 +1034,104 @@ void CInode::build_backtrace(int64_t location, inode_backtrace_t* bt)
>>    }
>>  }
>>  
>> +struct C_Inode_StoredBacktrace : public Context {
>> +  CInode *in;
>> +  version_t version;
>> +  Context *fin;
>> +  C_Inode_StoredBacktrace(CInode *i, version_t v, Context *f) : in(i), version(v), fin(f) {}
>> +  void finish(int r) {
>> +    in->_stored_backtrace(version, fin);
>> +  }
>> +};
>> +
>> +void CInode::store_backtrace(Context *fin)
>> +{
>> +  dout(10) << "store_backtrace on " << *this << dendl;
>> +  assert(is_dirty_parent());
>> +
>> +  auth_pin(this);
>> +
>> +  int64_t pool;
>> +  if (is_dir())
>> +    pool = mdcache->mds->mdsmap->get_metadata_pool();
>> +  else
>> +    pool = inode.layout.fl_pg_pool;
>> +
>> +  inode_backtrace_t bt;
>> +  build_backtrace(pool, &bt);
>> +  bufferlist bl;
>> +  ::encode(bt, bl);
>> +
>> +  ObjectOperation op;
>> +  op.create(false);
>> +  op.setxattr("parent", bl);
>> +
>> +  // write it.
>> +  SnapContext snapc;
>> +  object_t oid = get_object_name(ino(), frag_t(), "");
>> +  object_locator_t oloc(pool);
>> +  Context *fin2 = new C_Inode_StoredBacktrace(this, inode.backtrace_version, fin);
>> +
>> +  if (!state_test(STATE_DIRTYPOOL)) {
>> +    mdcache->mds->objecter->mutate(oid, oloc, op, snapc, ceph_clock_now(g_ceph_context),
>> +				   0, NULL, fin2);
>> +    return;
>> +  }
>> +
>> +  C_GatherBuilder gather(g_ceph_context, fin2);
>> +  mdcache->mds->objecter->mutate(oid, oloc, op, snapc, ceph_clock_now(g_ceph_context),
>> +				 0, NULL, gather.new_sub());
> 
> This mutate() call clobbers op in the Objecter::Op ctor (to avoid a bit of 
> extra work).  It needs to get rebuilt in the loop below..
> 
> Otherwise, looks good!
> 
Updated patch. "git://github.com/ukernel/ceph.git wip-mds" is also updated

---
From 38b909b5d1f5092d6b04b3c7669e21afd12151fb Mon Sep 17 00:00:00 2001
From: "Yan, Zheng" <zheng.z.yan@intel.com>
Date: Fri, 17 May 2013 16:43:01 +0800
Subject: [PATCH 25/32] mds: bring back old style backtrace handling

To queue a backtrace update, current code allocates a BacktraceInfo
structure and adds it to log segment's update_backtraces list. The
main issue of this approach is that BacktraceInfo is independent
from inode. It's very inconvenient to find pending backtrace updates
for given inodes. When exporting inodes from one MDS to another
MDS, we need find and cancel all pending backtrace updates on the
source MDS.

This patch brings back old backtrace handling code and adapts it
for the current backtrace format. The basic idea behind of the old
code is: when an inode's backtrace becomes dirty, add the inode to
log segment's dirty_parent_inodes list.

Compare to the current backtrace handling, another difference is
that backtrace update is journalled in EMetaBlob::full_bit

Signed-off-by: Yan, Zheng <zheng.z.yan@intel.com>
---
 src/mds/CInode.cc          | 112 +++++++++++++++++++++++++++++++++++++++++++++
 src/mds/CInode.h           |  13 +++++-
 src/mds/LogSegment.h       |   2 +
 src/mds/MDCache.cc         |  12 ++++-
 src/mds/MDLog.cc           |   1 +
 src/mds/Migrator.cc        |   6 ++-
 src/mds/Server.cc          |  16 +++++--
 src/mds/events/EMetaBlob.h |  16 +++++--
 src/mds/journal.cc         |  13 ++++++
 9 files changed, 180 insertions(+), 11 deletions(-)

[25/30] mds: bring back old style backtrace handling

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